Thermostat



March 26 1940-r E. K. CLARK 2,195,000

THERMOSTAT Original Filed Ct. 27, 1938 2 Sheets-Sheet 2 79 @fV L46 //vmz W|TNESSES INVENTOR 'ar/ K C/arK.

'ATTORNEY Patented Mar. 26, 1940 UNITED STATES PATENT OFFICE am. f' y minclsrammismammtowminghouee Electric t Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylappuoaaon mm zr, 193s, serial No. 231,210 Renewed November-16, 1939 My invention relates to thermostats, and more particularly to a method of controlling the operations of the bimetallic member of a snap-acting bimetallic thermostat. J

An object of my invention is to provide a thermally sensitive nat-iron thermostat capable of operating on a very low differential of temperature so that such thermostat may be directly mounted upon the iron sole plate and respond to the temperature variations thereof.

Anotherobject of my invention is to provide a bimetallic snap-acting thermostat having an adjusting device operatively associated with the bimetallic member thereof so as to substantially eliminate any relative movement between the adjusting device and the bimetallic member or the supporting base as the bimetallic member snapsfrom oil to on" and "on to o A further object of my invention is to provide a thermostat including a bimetallic member having a central strip and two exterior strips with a resilient adjusting member which has a snapon, resilient, fulcruming engagement with the bimetallic member for retaining and adjustably varying the operation of such bimetallic member.

A still further object of my invention is to provide a thermostat including a bimetallic member with a movable contact assembly comprising a U-shaped bracket and a contact plate rockably fulcrumed to the bracket within hour-glassshaped apertures positioned within the sides of the bracket. l

Another object of my invention is to provide an emcient, inexpensive, rugged bimetallic thermostat capable of handling at least 1500 watts witha very narrow temperature diilerential throughout its complete operating range.

A further object of my invention is to provide a snap-acting ilat-iron thermostat which may be 4'.) rigidly attached to the sole plate thereof to provide direct thermal conduction therebetween.

Other objects of my invention will either be pointed out specically in the course of the iollowing description of a device embodying my intion.

In the accompanying drawings:

Figure l is an elevational and partial sectional view of an iron and thermostat embodying my 60 invention;

Figs. 2 and 3 are top and side elevational views, respectively, of the thermostat embodying my invention;

Figs. 4 and 5 are sectional views, respectively.

vention, or will be apparent from such descriptaken along the lines IV-IV and V-V of'Fig. 3;

(Q1. #Mi-189) F18. 6 is a side view of the contact assembly before being fabricated;

Figs. I and 8 are side and end views of the bracket included in the contact assembly;

Fig. 9 is a plan view of the contact plate ineluded in the contact assembly;

Figs. 10, 11 and 12 are top, side and end views oi' the intermediate adjusting member included in the thermostat embodying my invention;

Fig. 13 is a fragmentary enlarged view of a portion of the adjusting member shown in Fig. 12;

Fig. 14 is a view taken along the line XIV-XIV oi' Fig. 10; n

Figs. 15 and 16 are top and side views, respectively, of the bimetallic member and mounting means therefor; and

Fig. 17 is an enlarged perspective view of the movable contact assembly.

Referring to the accompanying drawings, I show a bimetallic thermostat I0 comprising an irregularly shaped supporting structure or base I2, a bimetallic thermal responsive member I4, a movable contact assembly I6 rigidly attached to and insulated from the free end of the bimetallic member, stationary contacts I8 rigidly attached to and insulated from the supporting base I2 and positioned so as to be operatively associated with a movable contact assembly I6, an intermediate adjusting member 20 having a snapon and resilient fulcruming yengagement with the bimetallic member I I, and an adjusting member 22 for adjusting the operation of the bimetallic. member Il and movable contact assembly I6.

The supporting structure or base I2 is, in this instance, formed from a single sheet of metal. However, it is to be understood that such structure may be formed from a plurality of elements or molded from a phenolic resinous material, or made in any other desired manner. The supporting structure I2 includes,'in this instance, a horizontally positioned, forward or outwardly extending upper ledge or supporting shelf 30. Two lower forward or outwardly extending feet 32 are provided. which extend substantially parallel to the upper main supporting ledge 30, for rigidly attaching the structure I2 to the sole plate of an iron or any other suitable appliance, and a single forward or outwardly extending lug 3l cooperates with the bimetallic member I4 to limit its downward movement. The main supporting ledge has. a centrally disposed vertically extending threaded aperture 36 for receiving the adjusting means 22, a plurality of apertures 38 within one end thereof for rigidly attaching the adjusting member 26 thereto, a plurality 0f substantially L-shaped apertures 39 for permitting the depending fingers-16 of the adjusting member to pass therethrough, and a plurality of apertures within the other end thereof for receiving the stationary contacts i6. The feet or supporting members 32 have centrally disposed apertures 42 located therein permitting direct connection with the sole plate of the iron to afford good thermal communication therebetween, as shown in Fig. 1. In addition, the left support member 32 has an upwardly extending counterbore 43 to readily receive the bimetallicmember-supporting rivet 64.

The bimetallic thermal responsive member I4 (see also Fig. 15) comprises, in this instance, a

unitary bimetallic element having a central strip 44, two exterior strips 46, and two end portions 48 and 50, all formed by means of laterally positioned elongated slots 56. It is to be understood that, if desired, the bimetallic member I4 may be constructed from a plurality of members so as to form a functionally integral structure, substantially as described. The central strip 44 has transversely extending notches 52 located substantially at the midpoint thereof to cooperate with the adjusting member 2li, substantially as hereinafter described. The end portion 50 has a rivet structure 54 rigidly attached thereto which permits the bimetallic member I4 to be rigidly attached to the supporting structure I2 without altering the preset thermal characteristics of such member, in a manner set forth in the E. K. Clark and P. R. Lee copending application Serial No. 225,354, filed August 1', 1938, and assigned to Westinghouse Electric 8a Manufacturing Company. The bimetallic member I4 will thus be in direct thermal communication with the sole plate 45 of a flat iron, or the like, as shown in Fig. 1. The exterior strips 46 of the preferred bimetallic member i4 may have a plurality of waves 56 formed therein. These waves or deformations are formed to ensure a snap-acting toggling action of the bimetallic member. An aperture 66 is positioned within the end portion 48 of the bimetallic member I4 to permit the contact assemblyv I6 to be rigidly attached thereto, substantially as hereinafter described.

The movable contact assembly I6, as shown in Figs. 6, '7, 8 and 17, includes, in this instance, a supporting bracket 62 and a contact plate 64 flexibly attached thereto. The supporting bracket 62 is substantially U-shaped with upwardly extending side portions 68 and a base 69, as shown inFig. 6. The upwardly extending sides 68 are originally bowed slightly outwardly to permit the contact plate 64 to be readily assembled therewith, as hereinafter described. Hourglass-shaped apertures 66 are positioned within the upwardly extending side portions 66 of the U- shaped brackets 62 to cooperate with the contact plate 64.

The contact plate 64, as shown in Figs. 8 and 9, is relatively thin with respect to its width and length. The thickness of the plate 64 is substantially equal to the shortest transverse or vertical distance across the hour-glass-shaped aperture to prevent any relative vertical movement thereof, as hereinafter described. outwardly-extending transversely-disposed tongues 10 of substantially the same length as the apertures 66 are positioned on either side at substantially the midpoint thereof. The tongues 10 are adapted to be positioned within the hour-glass-shaped aperture 62 so as to iiexibly or fulcrumly cooperate with the upwardly extending sides 6l of the U-shaped brackets 62. When uniting the contact plate 64 with the U-shaped bracket 62, such contact plate 64 (Fig. 9) is positioned upon such bracket within the outwardly diverging sides 66, as shown in Fig. 6. The tongues 10 are then positioned in line with the hour-glass-shaped apertures 66. The side walls 68 of the bracket 62 are then pressed into an upright position substantially normal to the base 69, as shown in Fig. 1, with the tongues 1I) extending through the apertures 66.

The contact plate 64 will then be, rockably, fulcrumly or flexibly attached to the bracket 62 and will be permitted to rock or swing about a transverse axis extending through the midpoint of the tongues 10 or apertures 66. However, due to the plate 64 and tongues 10 having a thickness substantially equal to the shortest vertical distance across the hour-glass-shaped apertures, there can be substantially no vertical movement of the plate 64 with respect to the bracket 62, regardless of the angular position of the plate 64. It is preerred that suitable contacts 12 be rigidly attached to substantially the ends of the contact plates 64 to cooperate with the stationary contacts I6.

The movable contact assembly I6 is rigidly attached to the free or movable end portion 48 of the bimetallic member I4 by having a suitable rivet 96 (see Figs. 3 and 5) positioned through the apertures 60 of the bimetallic member I4 and the aperture 6I in the U-shaped bracket 62, whereupon the upper end of the rivet 96 is spun over against the U-shaped bracket 62 substantially as shown at 98 in Fig. 5. The U-shaped bracket 62 is thus rigidly attached to the free end of the bimetallic member I4 and will move with such bimetallic member. The U-shaped bracket and movable contact assembly I6 is, preferably, insulated from the bimetallic member I4 by using suitable insulating washers and sleeves (see Fig.

The stationary contacts I6 being two, in this instance, comprise a main contact portion 90 and an upwardly extending rivet portion 92. The contacts I6 are rigidly attached to the outwardly extending supporting ledge 30 of base I2 by having the upwardly extending rivet portion 92 inserted through the apertures 40 located within the ledge 30, whereupon the upper end of said rivets are, for example, spun over tightly against the upper surface of the ledge 30, as shown at 95, Fig. 5. Suitable insulating washers and sleeves 94 may be positioned between the main body portion 90 and rivet portion 92 of the contacts I8 to properly insulate them from the supporting structure I2. Suitable terminal straps 91 may be associated with the stationary contacts to afford means for connecting the thermostat to the circuit (not shown) which it is desired to have such thermostat control.

The intermediate adjusting member 20, shown in Figs. 10 to 14, inclusive, comprises, in this instance, a main body portion T4 and downwardly converging ngers or prongs 16 near one end thereof. The adjusting member 20 is preferably formed of a resilient material to permit the fingers 16 and the body portion 14 to be moved to a limited extent substantially along the longitudinal axis of the fingers 16 and to permit the lower end of the fingers 16 to produce a biasing action substantially along their transverse axis. for a purpose hereinafter described.

The main body portion 14 of the intermediate adjusting member 20 has a plurality of apertures 86 positioned at one side to permit the adjusting member 26 to be rigidly attached to the supporting structure I2', with the fingers 16 depending from both edges of the other side of the main portion 14. A semi-circular notch 88 is positioned within the portion 14 intermediate the depending fingers 16 to permit the adjusting member 26 to be positioned about the adjusting screw 22 and to permit the fingers 16 to be positioned one on either side of such adjusting screw. Lips 84 extend outwardly from the main portion 14 of the adjusting member 26 one on either side of the notch 88, and intermediate `such notch 88 and the respective depending fingers 16. 'I'he lips 84 have a downwardly extending semi-cylindrical groove 86 therein to cooperate with the adjusting screw 22, as hereinafter described.

The depending fingers 16 of the adjusting member 26, as shown in Figs. 1l and 12, are relatively narrow, and have an upper section 13 which extends substantially normal to the main portion 14, an intermediate inwardly tapering section 15, and a lower tip or gripping section 8|. Each gripping section 8| has a notch 18 in the upper portion of its inner edge, to engage the central strip 44 of the bi-metallic member I4, as shown in Fig. 4 and as hereinafter more fully described. The inner edge 19 of the lower portion of each gripping section 8| tapers outwardly from the notches 18 to permit a snap-on connection between the fingers 16 and the bimetallic member I4 (see Fig. 13). 'Irhe notches 18 are of such shape to permit free cooperation with the notches 52 and central strip 44 of bimetallic member I4, as will be hereinafter more fully described.

The adjusting screw or means 22 is, in this instance, a shaft threadedly engaged with the upper main supporting leadge 36 of support I2 through cooperation with the threaded aperture 36, and is adapted to extend outside the iron to permit an operator to readily adjust the thermostat.|6 through'the cooperation of the adjusting member 26, as hereinafter described.

The adjusting screw 22, as shown in Fig. 3, has a threaded portion 83 located at substantially the lower end thereof and adapted to cooperate with the threaded aperture 36 in support I2. An annular notch 82' is positioned within the lower portion of the Screw 22 a short distance above the threaded portion 83. The notch 82 cooperates with the lips 84 of the adjusting member 26, so that as the adjusting screw 22 is rotated within aperture 36, the cooperation thereof with adjusting member 26 will adjust the operation of the bimetallic member I4, as will be hereinafter more fully described.

When assembling the thermostat I6, the sta-y tionary contacts I8 are rigidly and insulatedly attached to the supporting ledge 36 as hereinabove described. The movable contact assembly I6 is rigidly attached to the bimetallic member I4 so as to be in cooperative alignment with the stationary contacts I8. The bimetallic member I4 is then rigidly attached to one of the supporting feet 32 by having the attaching rivet 54 positioned within the aperture 42 therein and rigidly attached thereto by having the lower end of such rivet spun over tightly against the supporting foot 32, within the counterbore 43, in accordance with the teachings of Clark and Lee as set forth in their above-identified copending application. 'I'he bimetallic member I4 is thus positioned substantially along the longitudinal axis of the thermostat I6 with the movable contact assembly I6 located substantially vertically above the lug or ledge 34, which, as the thermostat I6 is opened or disengaged, limits the downward movement of the bimetallic member.

The adjusting screw 22 is then inserted within the threaded aperture 36 and located so that the annular notch B2 will be substantially in line with the top surface of the supporting ledge 36. The adjusting member 22 is then positioned upon the supporting ledge 30 with the lips 84 extending into and cooperating with the notch 82 as the fingers 16 are positioned through the L-shaped apertures 39. See Fig. 3. The apertures 86 will then substantially fall in line with the apertures 38 located in the ledge 36 whereupon suitable rivets I62 may be positioned therethrough to rigidly attach one end of the adjusting member 26 to the supporting structure I2. As the adjusting member `is positioned upon the supporting structure I2 with the downwardly extending fingers 16 projecting through apertures 39, such fingers are positioned substantially in line with, and one on either sid of, the adjusting screw 22.

As the intermediate adjusting member 26 is positioned upon the supporting structure I2 with the downwardly extending fingers 16 extending through the supporting ledge 36, the gripping sections 8| of such ngers 16 will engage the central strip 44 of bimetallic member I4. Inasmuch as such fingers" 16 are formed of a resilient material, Athe tapered edges 19 thereof will cause the fingers 16 to be spread apart as they are forced'down upon the bimetallic member, so that such fingers will slide over and within the notches 52 in the central strip 44 of the bimetallic member I4.

As the fingers 16 are slid down along the cen- 'tral strip 44 within the notches 52 therein, the

notches 18, within the fingers 16, will cooperate with the notches 52 in central strip 44 of bimetallic member I4, and establish a snap-on or resilient connection therewith. The notches 52 in the central strip 44 will prevent any relative movement between the fingers 16 of the adjusting member 26 and bimetallic member I4 along the longitudinal axis of the bimetallic member I4. movement between the fingers 16 and bimetallic member I4 along the longitudinal axis of the fingers 16 or normal to the plane of the bimetallic members I4. Accordingly, it is obvious that there will be no relative movement between the adjusting member 26 and bimetallic member I4.

However, it is apparent that inasmuch as the fingers 16 of adjusting member 26 resiliently engage the bimetallic member I4 through the cooperation of notches 18 and 52, the' bimetallic member will be free to fiex from one position to another about such engagement as a fulcrum. However, such flexing action" will occur Without any relative linear movement between such adjusting member and bimetallic member at the fulcrum.

As the intermediate adjusting member 26 is positioned upon the supporting structure I2, the lips 64 cooperate with the adjusting screw 22 by extending into the annular notch 82 therein. 4These lips 84, after the adjusting member 26 is rigidly attached to the support I2, are biased downwardly against the screw 22 at all times, regardless of the position of such screw. This cooperativelaction between the lips 84 and ad- The notches 18 will prevent any relative .lusting screw 22 then enal .s the longitudinal u or vertical movements of the adjusting screw 22 to be accurately transmitted to the central strip u of the bimetallic member I4, through the cooperation of the ngers 16 at all times without any lost motion.

It, therefore, follows that, as the screw 22 is moved upwardly, the force applied to the adjusting member will also be in an upward direction along the adjusting screw 22 as shown by the arrow A in Fig. 4. This force will be applied to the bimetallic member I4 through the lingers 1G, and due to their inwardly tapered conguration will be applied in the direction of such iingers and arrow B, in Fig. 4. Accordingly, the lower end or gripping section 11 of the fingers T6 will be biased inwardly substantially as shown vby arrows C in Fig. 4. This condition ensures a positive, resilient, gripping, snap-on connection between the -adjusting member 20 and the bimetallic member i4 at all times, as well as permitting the bimetallic member I l 'to freely flex thereabouts at all times.

As the bimetallic member Il iiexes from an off to an on or from an on to an off position, there is a momentary period at which tnere will be substantially no direct force between the bimetallicmember I4 and its supportlng structure, namely, the adjusting screw 22 and the fingers 16. However, due to the down- Ward biasing action of the resilient adjusting member 20, whereby the lips 84 are biased against the lower surface of the annular notch 82 and due to the transverse resilient action between the fingers 16 and the central strip 4I, it is apparent that there will be no loose or free movement between any of the cooperating parts or the bimetallic member H, adjusting member 20 and adjusting screw 22. This feature permits the thermostat I0 to be accurately or exactly adjusted to a very close temperature differential at all times.

The movable contact assembly I6, being rig- .dly attached to the free end of the bimetallic member i4, moves therewith. However, inasmuch as the contact plate 64 is iiexibly or rockably fulcrumed within the hour-glass-shaped apertures located in the side walls of bracket 62, it follows that the movable contacts 12 positioned upon the plates 64 will have a relatively loose free movement with respect to the stationary contacts I8. This ensures a positive engagement of -equal pressure between both stationary contacts and the movable contacts at all times.

The downward movement of the movable contact assembly I6 and free end of the bimetallic member I4 is limited by the lug 34, and may be varied by adjusting the relative position thereof. This adjustment controls the thermal amplitude or sensitivity of the completed thermostat.

It is, therefore, obvious that the device embodying my invention provides a thermally sensitive flat-iron thermostat capable of handling at least 1500 watts with a very narrow temperature differential having an adjusting means operatively associated with the bimetallic snap-acting member so as to substantially eliminate any relative movement therebetween, and a movable contact assembly including a contact plate which is free to rock or ex with respect to the bimetallic member, but is prevented from substantially any bodily vertical movement with respect thereto.

Various modifications may be made in the device embodying my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and the appended claims.

I claim as my invention:

l. A thermostat comprising, in combination, a bimetallic thermal responsive member and an adjusting member having resilient portions for yieldingly engaging such bimetallic member at all times.

2. A thermostat comprising, in combination, a bimetallic thermal responsive member having a central strip and two exterior strips and an adjusting member having a resiliently gripping connection with the central strip of such bimetallic member.

3. A thermostat comprising, in combination, a supporting structure, a bimetallic thermal responsive member rigidly attached to the structure, and an adjusting member attached to the base having means for resiliently engaging the bimetallic member.

4. A thermostat comprising, in combination, a supporting structure, a bimetallic thermal responsive member having a central strip and two exterior strips rigidly attached to the structure and in direct thermal communication with the supporting structure, and an adjusting member rigidly attached to the structure having an operative connection with the central strip of such bimetallic member.

5. A thermostat comprising, in combination, a strip-type bimetallic thermal responsive member, and an adjusting member having a fulcruming connection with both edges of such bimetallic member.

6. A thermostat comprising, in combination,

a supporting structure, a bimetallic thermal responsive member having a central strip and two exterior strips rigidly attached to the structure and in direct thermal communication with the supporting structure, and a pronged adjusting member attached to the structure having a resilient and fulcruming connection with the central strip of the bimetallic member.

7. A thermostat comprising, in combination, a supporting structure, a bimetallic member, an intermediate member resiliently engaging the bimetallic member, and an adjusting means operatively associated with the intermediate member for adjustably moving such member and varying the operation of the bimetallic member.

8. A thermostat comprising, in combination, a supporting structure, a bimetallic member, an intermediate member attached to the structure at one end and resiliently engaging the bimetallic member at the other end, and an adjusting means operatively associated with the intermediate member intermediate the ends thereof for adjustably moving such member and varying the operation of the bimetallic member.

9. A thermostat comprising, in combination, a supporting structure, a bimetallic thermal responsive member having a central strip and two exterior strips rigidly attached to the structure and in direct thermal communication with the supporting structure, an intermediate member attached to the structure at one end and resillently engaging the central strip of the bimetallic member at the other end, and an adjusting screw operatively associated with the intermediate member intermediate the ends thereof for adjustably moving such member and varying the operation of the bimetallic member.

10. A thermostat comprising, in combination, a bimetallic thermal responsive member, having a central strip and two exterior strips, an adjusting member having means for resiliently engaging the central strip of the bimetallic member, and a iiexibly mounted movable contact rigidly attached to the bimetallic member.

l1. A thermostat comprising, in combination, a supporting structure, a bimetallic thermal responsive member having a central strip and two exterior strips rigidly attached to the structure and in direct thermal communication with the supporting structure, a movable contact assembly attached to the bimetallic member having a ilexibly mounted contact plate, an intermediate member resiliently engaging the bimetallic member, andan adjusting means operatively associated with the intermediate member for adjustablymoving such member and varying the operation i the bimetallic member and movable contact assembly.

12. A thermostat comprising, in combination, a bimetallic member, and an adjusting member having a main portion and two depending fingers which engage the bimetallic member.

13. A thermostat comprising, in combination, a bimetallic member, and a resilient adjusting member having a main portion and two depending ngers which resiliently engage the bimetallic member.

14. A thermostat comprising, in combination, a bimetallic member, and an adjusting member including a main portion and two depending ngers having a notched inner surface constituting a transverse snap-on connection with the bimetallic member.

15. A thermostat comprising, in combination, a supporting structure, a. bimetallic thermal responsive member having a central strip and two exterior strips rigidly attached to the structure, an adjusting member including a main, portion rigidly attached to the structurey and two depending ilngers having a resilient transverse en gagement with the central strip oi the bimetallic member.

a supporting structure, a functionally integral a bimetallic member having a central strip and two exterior strips rigidly attached to the structure in direct thermal communication with such structure, a movable contact assembly attached to the bimetallic member comprising a U-shaped bracket having hour-glass-shaped apertures positioned within the sides thereof and rigidly attached to the member and a contact plate fulcrumed to the bracket within said apertures, a resilient intermediate member, comprising a main portion and two depending ingers, attached to the supporting structure at one end by the main portion and having a resilient transverse engagement with the central strip of the bimetallic member at the other end, and an adjusting member threadedly engaged with the supporting structure and operatively associated with the main portion of the intermediate member for adjustably moving such member and for varying the operation of the bimetallic member and movable contact assembly.

17. In a vthermostat including a bimetallic member having a plurality of strips, a resilient member engaging one of the strips for hunting the movement thereof, and adjusting means operatively associated with the resilient member for adjusting the operations of the member and biber.

maar. K. CLARK. 

